Referring to FIG. 1, a conventional side-edge type backlight module includes a light guide plate 11, a light bar 12 provided on a lateral side of the light guide plate 11, a plurality of thermally conductive sheets 13 adhered on the back of the light bar 12, a heat dissipating seat 14 connected to the thermally conductive sheets 13, a base frame 15 including a base wall 151 and a side wall 152 that cooperatively define a receiving space for receiving the light guide plate 11, the light bar 12 and the heat dissipating seat 14 therein, and a cover 16 including an upper plate 161 and a side plate 162 cooperatively covering the base frame 15. The light bar 12 is constructed by soldering a plurality of light-emitting diodes 121 (only one is shown) to a printed circuit board (PCB) 122.
Through the aforesaid structure of the conventional side light type backlight module, the thicknesses of the printed circuit board 122 of the light bar 12, the thermally conductive sheet 13, the heat dissipating seat 14, the side plate 152 of the base frame 15 and the side plate 162 of the cover 16 will lead to a wide border situation on four sides of the light guide plate 11. To illustrate with more details, as shown in Table 1 below, by means of actual measurement, the thickness (d1) of the printed circuit board 122 is approximately 1.7 mm, the thickness (d2) of the thermally conductive sheet 13 is approximately 0.25 mm, the thickness (d3) of the heat dissipating seat 14 is approximately 2.2 mm, the thickness (d4) of the side plate 152 of the base frame 15 is approximately 0.8 mm, the thickness (d5) of the side plate 162 of the cover 16 is approximately 1.4 mm, and the interval (d6) between the side plates 152, 162 of the base frame 15 and the cover 16 is approximately 0.1 mm, so that the overall thickness (i.e., d1+d2+d3+d4+d5+d6) is approximately 6.45 mm. It is evident that the overall volume and area of the conventional backlight module are increased, while the scope of the area thereof is reduced. Moreover, heat generated by the light bar 12 is firstly transmitted to the heat dissipating seat 14, and is then dissipated outward through the base frame 15 and the cover 16, so that the heat dissipation effect of the conventional backlight module is poor. Thus, how to make the border of the backlight module narrow, how to enlarge the scope of the area thereof and how to enhance the heat dissipation effect are issues that need to be resolved in the industry.
TABLE 1ComponentThickness (mm)Printed circuit board1.7(122)Thermally conductive0.25sheet (13)Heat dissipating seat2.2(14)Side plate (152) of the0.8base frame (15)Side plate (162) of the1.4cover (16)Interval between the0.1side plates (152, 162)of the base frame (15)and the cover (16)Overall thickness6.45